Monochoria hastata

Name and classification

Monochoria hastata (L.) Solms-Laub.
Family Pontederiaceae

Common names

arrowleaved monochoria

Disseminule

seed

Description

Fruit a capsule with numerous seeds. Seeds terete, elliptic to broadly elliptic, occasionally broadly oblong in outline, 0.6–0.83 mm long, 0.4–0.57 mm in diameter; with ca. 12 longitudinal lines or low ridges evenly spaced around seed. Testa light yellow to orange-yellow, frequently darker reddish on one or both ends, with glistening, fine horizontal striations in between ridges. Hilum terminal, often with persistent funiculus remnant to 0.1 mm long; chalazal end obtuse or sometimes even depressed and often darker in color. Embryo axile-linear, extending almost to both poles; endosperm readily visible.

Identification considerations

Seeds develop from an anatropous ovule, characteristic in the Pontederiaceae, resulting in both ends being distinctly featured. The chalazal end is opposite the hilar end.

Similar species

Eichhornia crassipes (Sw.) Kunth (non-FNW)

Heteranthera limosa (Sw.) Willd. (non-FNW)

Eichhornia azurea (Sw.) Kunth

Monochoria vaginalis (Burm. f.) C. Presl

Distribution

tropical Asia, from India through Southeast Asia; also China, Northern Australia, Fiji, and Hawaii

Habitat

shallow water; freshwater pools, mudflats in rivers, ditches, canal banks, swampy ground, rice fields

General information

Monochoria hastata is an attached aquatic herb with emersed leaves to 100 cm tall. Although it is not as common nor as serious a weed as M. vaginalis, it is widespread in tropical Asia and is an aggressive weed of lowland rice in Fiji, Malaysia, the Philippines and Indonesia. Monochoria hastata has been grown as an ornamental in water gardens, and the entire plant except its roots is eaten in India.

seeds

seeds

seeds

seeds

A, seed; B, longitudinal section of seed showing embryo; C, transection of seed; drawing by Lynda E. Chandler

A, seed; B, longitudinal section of seed showing embryo; C, transection of seed; drawing by Lynda E. Chandler

chalazal end of seed

chalazal end of seed

hilar end of seed

hilar end of seed

surface detail of seed

surface detail of seed